Since then, the world has changed. Most wars now are seen to be about religion and ethnicity and the type of conflict we had here registers as normal, not absurd.

But our neighbours continue to patronise us, to congratulate themselves in having brought sanity to Northern Ireland while continuing to indulge a sense of their being different.

You would think, from these attitudes, that Irish sectarianism was a rare flower that simply doesn't grow and flourish outside its native soil.

In fact, we exported it to wherever stout is still enjoyed in Irish pubs.

As the Irish migrated to the US and Canada, to the English and Scottish cities and to Australia, they took their divisions and animosities with them.

It ill behoves anyone who knows those communities to react as if sectarianism was something merely strange and shocking.

One of the institutional representations of that division is in Scottish football, which Scottish politicians would have us believe can be only concerned with the game itself.

In fact, the meeting of Celtic and Rangers on the pitch is always a replay of the ancient drama of Protestant and Catholic warfare.

There may be thousands of people who would like it to be about something else. They have a right to work for that. They don't really have a right to pretend that history didn't happen.

But sectarianism does wilt in foreign soil. Older people remember it in Toronto and parts of the US.

I have an American friend who tells me his own grandmother refused all her life to speak to Protestants for she held them to blame for her having had to leave Ireland.

And if we knew why the flower wilts in some soil and continues to thrive in Northern Ireland and in parts of Scotland, we might understand better how to kill it off altogether.

Scotland is deeply embarrassed by it, a remnant of a tradition it would like to feel free to regard with mere contempt.

It is important to the Scottish that they can think of themselves as not being like us.

When the Catholic composer James MacMillan wrote of sectarianism as Scotland's shame, many rallied to say that he was spouting nonsense.

Many of them genuinely didn't believe what he said, because they lived in areas where there was no division on Catholic-Protestant lines.

The journalist Joyce MacMillan challenged Scots to say how they felt about their flag, the Saltire, being flown from lamposts in Belfast.

When Jason Campbell, jailed for killing a schoolboy Celtic supporter with a Stanley knife, claimed he was in the UVF and asked for a transfer to Long Kesh, the Scottish parliament was appalled and refused, knowing that he would qualify for early release if in prison here.

He was to be defined as a different kind of killer from the type we had had to endure. That was an important, but meaningless distinction in the Scottish mind.

And when Lindsay Robb, who had been part of the PUP talks team, applied for a place at Stirling University, he was rejected on the grounds that he had been a terrorist. Here we think it's better if our terrorists do go to university; it tends to turn them into nicer people.

James MacMillan says that he was misquoted when he was reported describing Glasgow as "Belfast without the bullets".

The sectarian weapon of choice in Scotland is the knife. Now it is the bomb, with devices having been sent to Celtic manager Neil Lennon and others, in what is either a grisly escalation of a familiar tradition of sectarian malice, or an expression of individual madness. MacMillan's primary concern is that Scotland holds the Catholic Church in contempt. His argument is not a defence of Celtic against Rangers, or Irish republicanism against loyalism.

He doesn't actually resonate much with the street-level quarrels - it's hard to imagine anyone getting knifed for going to one of his concerts - yet the reaction when he spoke showed that he had touched a nerve.

Scotland is protesting too much about how unsectarian and normal and secular and not like Northern Ireland it is.

And while not wanting to exaggerate the problem there, it should worry us that the old simmering social and ethnic toxins have not been neutralised there.

There is a simple theory for why Irish sectarianism died out in New York, Toronto and Sydney: the Irish there were not split over pressing political concerns.

But what keeps sectarian bitterness alive in Scotland? Football? Proximity to Northern Ireland, where thumping, truculent bands can stomp out their rage on Belfast streets and come home on the ferry? Or something else?

We would be as well trying to find out, for the remnant of sectarian violence in Scotland suggests that we might here resolve all our political problems in a rapidly-secularising society and still, at the end of it, be waking occasionally to the news that a schoolchild has been knifed, or that a sportsman has received a bomb in the post.

And all we will have then to say in response is what the Scots say this week: 'I don't understand.'